Method of electrodepositing precious metals and apparatus for practicing the same



Dec. 22, 1931. BART 1,837,193 7 METHOD OF ELECTRODEPOSITING PRECIOUS METALS AND APPARATUS FOR PRACTICING THE SAME Filed June 8, 1928 filed. H20. NiduL INyENTOR lilaa'm s Bart,

ATTOR N EY Patented Dec. 22, 1931 UNITED STATES PATENT OF FICEl BLASIUS BAR-'1, OF EAST ORANGE, NEW JERSEY, ASSIGNOR TO PRECIOUS METALS DE- VELOPING 00., INO., OF NEWARK, NEW JERSEY, A CORPORATION OF NEW JERSEY METHOD ELEG'IBODEPOSITING PRECIOUS METALS AND APPARATUS FOR PRAO'IICING run sum Application filed June 8, 1928. Serial No. 283,997.

The invention relates in general to an improved method for the electrodeposition of precious metals and in an apparatus for commercial practice of the same.

In the art of electroplating articles with the so-called precious metals, it is the usual. practice to contain the preciousmetal in a solution in the electrolyte and subject relativel'y small articles as cathodes to the action of an electrolytic bath following conventional practices in this respect. In this prior art it is known to use platinum as the anode as such metal is inmluble in the electrolyte but econ= omy necessitated the use of a small size anode 5 when such as expensive metal was used. No

articles on any commercial prohibitive cost of providing an anode suffi i; ciently large to supply the requisite area of contact with the electrolyte. The anode sur face in electroplating with platinum and like metals should at all times be considerably larger than the cathode surface. An anode surface ofthe area requisite to plate large size articles is prohibitive.

One ofthe primary objects of this inven 30 tion is to provide ,of a la er of precious metal on a cathode surforan economic deposition face 0 relative large area.

In this specification and in the. claim, the term precious metal is sufiiciently generic to include any one of the following metals ruthenium, rhodium, palladium, osmium, iridium, chromium, platinum-and gold.

Broadly, theinvention is attained by containing the precious metal as a solution in the electrolyte periodically replenishing the metal to maintain the requisite percentage of metal in solution; but practicing the electrolytic deposit-ion on a relatively large area cathode, in the presence ofan anode formed of a non-precious metal which is insoluble in the electrolyte and whichpres'ents to the electrolyte the requisite large area of contact.

Referring to the apparatus aspect of the disclosure, an object of the invention is to provide an electrolytic 'bath'which will funcscale due to the},

tion economically in coating large size objects with any one of the preciousmetals and by means of which the method may be practiced commercially and efiiciently when practiced on a large scale.

Various other. objects and advantages of the invention will be in part obvious from a consideration of the method featuresof the disclosure and from an inspectiongof the accompanying drawing and in part will be more fully set forth in the following particular description of one method of practicing the invention, and the invention. also consists in certain new and novel modificationsof the preferred method and other features of construction and combinations of parts hereinafter set forth and claimed.

. In theaccompanying drawing, thefigure lllustrates an electrolytic bath by means of which the method herein featured may be practiced, and which illustrates a preferred embodimentof the physical aspect of this disclosure. 1 v

In the drawing, thereis shown a tank 10 constituting the ,anode and which forms or outlines a receptacle for containing the electrolyte 11. Conventional means are provided for connecting the positive lead 12 from a suitable source of electric energy. Positioned inthe tank is a cathode 13 and the showing is intended to represent some large .areaarticle to be coated such as an automobile radiator frame. The negative lead 14 is conventionally connected physically and electrically to the large size cathode.

The electrolyte 11 contains a solution of the precious metal which is to coat the cathode 13.

In the instant case, it may be assumed that the-electrolyte contains a phosphate of platinum employed in the case where it is desired to coat a radiator frame with a thin layer of electrolytically deposited platinum.

It is a feature of this disclosure that the anode, in this case the tank itselfjor a glass tank lined with electrolytic nickel, be insoluble in the electrolyte. The only metal known at present which will meet these requirements is electrolytically deposited nickel. It is believed that electrolytically deposited cobalt and perhaps electrolytically deposited chromium may eventually be utillized to form the tank or at least to constitute a linin for the tank. It is not known at this time w etherthe use of cobalt or chromium is commercially practicable.

It is noted that other metals usually used for the purpose of forming anodes, even rolled nickel, are unsuited for use as anodes in practicing the method herein featured. Nickel of the electrolytically deposited form is the only substance now used with entire satisfaction.

Another feature which is believed to contribute to the success of the method of coating large objects as herein outlined is that the area of anode exposed to the electrolyte is relatively large. Apparently the greater the exposure of area of anode the more efiicient is the operation. In the illustrated case,

where the anode forming tank has the oathode positioned therein, the area of anode exposed to the electrolyte is, of course, many times the area of cathode surface exposed to the electrolyte. It is within the scope of this disclosure to form the tank of some suitable material such as glass, porcelain or celluloid and the like and position the anode in the form of plates of electrolytically deposited nickel in such non-metal tanks.

As the amount of precious metal deposited on the cathode is extremely thin, it has been found that by following the method herein featured the coating of large objects at a cost which is not prohibitive for commercial practice is possible and as a matter of fact is only slightly more expensive than the coating of similar objects with certain of the non-precious metals such as silver. The large area of cathode in contact with the electrolyte permit s of a rapid deposition with resulting economy in the time necessary to effect the deposition and economy in current consumpt1on over known methods.

I claim:

An electrolytic bath including an electrolyte containing a solution of one of the preclous metals, and an anode of electr lytically deposited nickel insoluble in the electrolyte.

' Signed at Newark in the county of Essex and State of New Jersey this 31st day of May A. D. 1928.

BLASIUS BART. 

